Artificial covering units made of concrete are well-known to lay out pavements or covering wall surfaces on residential or commercial properties, for example defining the surface of walkways or patios. Such stones are advantageously relatively inexpensive to make, as opposed to natural carved flagstones, but the resulting pattern is often repetitive or has what is called in this field an unnatural “linear line effect”. Great efforts have been made to design artificial covering units which provide a more natural look, while still retaining the ease in their manufacture. It is worth mentioning that the expressions “covering unit”, “stone” and “flagstone” are used throughout the present description without distinction to define a unit used as a paving or as a building material.
Attempts have been made in the past to develop sets of artificial stones comprising stones of different shapes used in combination with each other for paving a surface. The natural random look in those cases is obtained by combining artificial stones of different shapes. However a major drawback with those sets is that they often become a real puzzle for the user to install and combine the stones in a proper way. Another drawback is that currently existing systems are limited in terms of possible types of installation. Most systems allow installation of the units according to either one of the rotational or the linear tessellation principle, but few offer the possibility of installing the units by rotation or linearly (by “running bond” or “stack bond”).
There is currently a need in the market for larger artificial stones, since they tend to provide a more natural and esthetic look. Larger artificial stones also provide better coverage per unit. However, one drawback of larger stones is that they are also generally heavier.
Known to the Applicant is U.S. Pat. No. 7,637,688, which describes a building unit made of primary elements which are rotational tessellation of one another. Since the building units are all based on a primary element, pavements created with such units tend to have a discernible pattern.
Also known to the Applicant is U.S. design D602173. This design shows two units which can be paired to form a hexagonal shape. While the paired units allow the creation of pavement with a rotational tessellation, it does not allow assemble the units in a stack bond or running bond configurations.
Thus, there is presently a need for a paving system that provides a natural random look, while at the same time being easy to manufacture at a reasonable cost, and easy to install for any unskilled person in either one of linear and rotational tessellations.